Steel roll



Patented Dec. 7, 1943 2,336,247 STEEL aoLL Wilford 0. Harris, Reiflton, Pa.

No Drawing. Application December 6, 1941,

Serial No. 422,010

4 Claims.

The invention pertains to an improvement in rolls for use in a hot mill and in the process of forming various types of plates or shapes.

One of the objects of the invention is to provide a roll of alloy steel having great strength and shock resisting qualities, capable of withstanding the heavy loads to which it is subjected in service. i

Another object of the invention is to provide a roll of alloy steel for use in a hot mill and being particularly suitable for such use, in that its construction is such as to avoid having fire checks or cracks formed on its outer surface.

A further object of the invention is the provision of a cast steel roll having thehardness of the metal adjacent the center of the roll substantially the same degree as the hardness of the metal forming the surface of the roll, and in this manner, the roll may, due to wear which takes place in service, be machined to present a roll of slightly less diameter than its original configuration and still, at the same time, sacrifice none of its original characteristics.

Heretofore, rolls for use as hot rolls in a roll mill have been made of cast steel or steel alloys in attempts to provide a dense, hard and tough roll of sufficient strength to withstand the shocks and blows to which the same are subjected and, at the same time, to limit the fire checks or cracks formed in the roll surface by use. These attempts have, in the main, not proved successful since, if the roll surface is hard, it has generally been brittle and where the surface is softer and more ductile to prevent fire checks, the wearing quality of the roll has suffered.

I have found that by combining certain hereinafter named elements into a charge, a steel roll may be formed which not only presents a hard surface to thereby render the roll wear resistant, but that the entire roll is of substantially the same hardness throughout. The distinct advantage thus gained is that during service, the roll will wear due to the great amount of stresses to which it is subjected and, after a continued use, to the stage at which ordinarily a cast roll mediately thereafter being subjected to a cooling medium to thereby set up great internal stresses in the roll structure.

The roll of the present invention is capable of rapid change of heat without rupturing the surface by the formation of firingcracks and,

while it will be understood that the absolute elimination of fire cracks is not possible, the checks formed in the surface of the roll embodying the present invention are of such minute 'dimension as to be microscopic and, therefore, of no consequence since they leave no counterpart impression upon the metal being worked and do not grow or enlarge as a result of the wide range of temperature to which the roll is subjected in service.

I flndin practice that these undesired elfects in the roll can be substantially eliminated and the production of a tough and exceptionally strong roll may be produced by first employing an amount of carbon less than thatrequired to form cast iron and by introducing a suflicient amount of copperwith the related proportion of molybdenum. A hardening agent in the form of manganese is also present with a rang of sulphur and phosphorus to reduce the brittleness of the finished product. A certain range of percentages of chromium is also added tomy alloy in order to enrich the charge and the amount of would be rendered useless, the roll of the present ing the hot metal being extremely heated and then advanced away from the hot metal and imchromium used is dependent upon the use to which the roll will be placed in service a well as some consideration being given to the siz of the ultimate roll to be produced.

It is to be noted that by the use of molybdenum and copper that neither oxidize and, upon using in the charge scrap rolls or rolls made previously from the herein contained combination of elements and which have, due to their usage and machining, been rendered unfit for continued service, a very slight amount of these two elements, namely molybdenum and copper, need be added to the charge to bring it within the hereinafter set forth proportions of elements.

In carrying out the invention, I. preferably employ the hereinafter set forth proportions or ranges of the above-mentioned elements:

.Per cent Carbon .35 to 2.00 Manganese .60 to 1.25 Silicon .30 to .60 Sulphur and phosphorus .06

Chromium .40 to 1.00 Copper .50 to 2.00 Molybdenum .20 to .60

It has also been found in practice that the most desired results are obtained by the following method of treatment or processing of a roll after it has been formed greatly to enhance the physical properties of the steelroll. Being processed by the following method, the roll formed by the above-mentioned elements has a Shore hardness of from 40 to 50 as well as having a high elastic ratio and great strength while at the same time being easily machined. The preferred method of treating the roll is first to normalize the metal thereof by subjecting the roll to a heat treatment of between 1600to 1700 F., and then allowing it to cool. The roll is again reheated with the best results attained by maintaining the second reheating temperature at 1,000 E, and allowing the roll to remain subjected to this constant temperature for approximately one hour for each one inch diameter of the roll so as to permit the heat to penetrate or reach the entire mass.

Other changes in the percentages may, of course, be made without departing from within the spirit of the invention and the scope of the appended claims.

I claim:

1. A steel roll for hot metal rolling mills, said roll comprising a maximum 01 2.00% carbon, 1.25% manganese, .60% silicon, .06% sulphur and phosphorus, 1.00% chromium, approximately 2.00% copper, and .60% molybdenum.

2. A steel roll for hot metal rolling mills, said roll comprising not more than 2.00% carbon,

5 .06% sulphur and phosphorus, together with approximately .20% to .60% molybdenum, .60% to 1.25% manganese, 30% to .60% silicon and .40% to 1.00% chromium, and approximately 2.00% copper.

l0 3. A steel roll for hot metal rolling mills comprising an alloy containing 35% to 2.00% carbon, .60% to 1.25% manganese, 30% to .60% silicon, .06% sulphur and phosphorus, .40% to 1.00% chromium, approximately 2.00% copper l5 and .20% to .60% molybdenum.

, 4. A steel roll adapted for hot metal rolling mills, said roll comprising an alloy containing a maximum of 2.00% carbon, .06 of equal portions of sulphur and phorphorus, about 20% to 20.60% molybdenum, about .60% to 1.25% manganese, about 30% to .60% silicon, about .40% to 1.00% chromium, and approximately 2.00% copper.

WILFORD C. HARRIS. 

